Why should a woman have such a low bar for a man?
Seriously OP, you yourself say he has masses of baggage, is in need of therapy, hasn't the best social skills, has poor economic prospects, is in his mid 40s but still thinks he's a good prospect for a woman.
Any woman going near him is going to be a bag full of problems. If he's autistic is he really going to be able to cope with that?
Add to that his age. Is it realistic he's going to find a woman who is ten years his junior? If he's not, then realistically he's looking at someone older than child bearing years. That means the ship has sailed for children. Unless he becomes a step dad.
See previous points.
Honestly, I don't think it's fair to any woman or children to be trying to match them with your brother. Your brother should be sorting his own life out and finding happiness from other things because a woman is not a magic bullet - she is not there to service the needs of a man. Women are not a service humans to a males. And that's essentially what we are talking here. It's her job to make him happy.
The only person who can make someone happy is yourself. At THAT point, you become a worthwhile partner and potentially a catch because you have something to offer. So his focus should be on that - that's hobbies, improving his life etc.
And in doing that, that's when he might find someone. No woman wants to be lumbered with a depressed man with a shed load of issues and few prospects. Any woman who puts up with it, is a massive problem in her own right and it's a recipe for disaster and he should be steering clear of for his own well being!
As his sibling, you need to be to the point on this because you aren't helping by being dishonest or trying to polish a turd. It's just a fantasy.
If he's got to 46 and in this situation, he is ultimately a significant part of the problem.
I think it's disrespectful to women to be posing this to women to somehow 'fix'. Men are not projects. Men are responsible for themselves.